Megajolt in application to a Pinto Capri queries MAP vs. TPS

Megajolted · Post by **Megajolted** » Sat Apr 07, 2007 11:21 am

Hello, I am planning to treat my engine to Megajolt.

I am running a 2.0 Pinto with a stock cam, egg port head and a downdraft 38Dgas Carb which has been bored out to flow much more air, as per Vizards guidance.

I am told that TPS is much easier and effective to use but I am not so sure.
Which is better!?

-As I have a stock cam and will not be ever upgrading to more than a FR cam, my pulses will never be too uneven.

-The Dgas flows a lot more air than standard, +2.5mm chokes and stub stack with smoothed restrictions. I think the MAP will be very receptive to this large pressure change over a TPS which doesnt account for temp and humidity either.

Does it source the pressure change from the same place the distributer draws its vacuum advance?

Lastly, Is the MAP option tricky to install over the TPS option?

Thanks, I can't wait to get stuck in!

Post by **brentp** » Sat Apr 07, 2007 5:14 pm

Hello,

The ever popular topic! We have a FAQ that covers this:
http://www.autosportlabs.net/Choosing_b ... MAP_or_TPS

My recommendation is that *if* you can get a source of stable vacuum, I'd go with the MAP sensor based setup because it more accurately measures engine load.

If you have individual runners, you can draw the vacuum from each runner as depicted in the link above.

Does the Pinto vacuum advance port sees manifold pressure 100% of the time, or does it become 'disabled' depending on throttle position (i.e. the port becomes obstructed..). The best way to find out is to see where the line goes- does it go to a spot on the manifold? I know that TR6's have individual runners, but the manifold has a bridge across all runners for the brake booster line. This is a perfect reference point for the MAP sensor.

Go TPS if:

1. If you can't get a stable vacuum reading, or are unwilling or unable to tap into the individual runners to create a source of stable vacuum (diagram in FAQ);
2. You have really aggressive cams that cause an unstable MAP reading due to camshaft overlap.

I hope this helps,
Brent

capri_turbo · Post by **capri_turbo** » Tue Apr 10, 2007 7:59 am

Go with the MAP sensor option... I'm running it on my Capri 2.1 with a Piper 285 cam, stage 3 head, 38 DGAS and it's absolutely fine. Been running MJLJ for almost a year now and it's the best thing I ever did to the engine. I did a Capri (pinto) specific installation guide on my website and an article for Capri Club International mag. If you have any specific questions re: Capri install, I can help.

Megajolted · Post by **Megajolted** » Tue Apr 10, 2007 6:44 pm

Excellent, I shall place an order for a MAP version v. soon

Thank you brentp. the vacuum hose connects to the carb base before it reaches any of the runners, this will be constant 100% of the time.

Thank you capriturbo, it's good to see you have MAP with a dgas and piper 285:- something I may upgrade to once I have megajolt! Had a quick look at your website, looks very detailed and useful, will study it now.

I've asked about ordering from a UK supplier, AFRacing, hope they reply soon or I'll order from the US.

Megajolted · Post by **Megajolted** » Tue Apr 10, 2007 6:52 pm

brentp wrote:
Does the Pinto vacuum advance port sees manifold pressure 100% of the time, or does it become 'disabled' depending on throttle position (i.e. the port becomes obstructed..). The best way to find out is to see where the line goes- does it go to a spot on the manifold? I know that TR6's have individual runners, but the manifold has a bridge across all runners for the brake booster line. This is a perfect reference point for the MAP sensor.

I've just read from Colin's site that the vacuum found at the base of the carb, which I was going to use, is not as great as the full manifold vacuum.

Plus the PCV valve connection, which goes into the manifold prior to branching, is fit for purpose

cheers

capri_turbo · Post by **capri_turbo** » Wed Apr 11, 2007 7:37 am

oh yes, you can't use the original vac advance line as it does not see full manifold vacuum hence getting the adaptors from Demon Tweeks (aprox £12 delivered). I had already removed the PCV due to the cam etc. and routed the crankcase breather to a small filter.

I brought all the wires and vac hose in through the oil pressure line grommet... you'll notice thare is an unused hole on it, which is perfect for this.

Good luck, and just shout if you need anything.

Col